LU-7346 tests: Reintroduce SLOW tests to review process

LU-7346 tests: Reintroduce SLOW tests to review process

Tests running for five minutes and more are considered to
be eligible to be marked as SLOW. After running tests
multiple times it was found, there are certain tests
which take under five minutes and hence can be
reintroduced in the normal review process.

Signed-off-by: Saurabh Tandan <saurabh.tandan@intel.com>
Change-Id: If638e41a8bf6c9418d69257b00cad964d0810a02
Reviewed-on: http://review.whamcloud.com/17143
Tested-by: Jenkins
Reviewed-by: James Nunez <james.a.nunez@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Wei Liu <wei3.liu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>